Patent Literature 1 discloses one known example of such a line light irradiation device. This line light irradiation device includes a casing having a left-right pair of side panels and a bottom panel with an opening formed at the top panel side, and a light-emitting unit that is positioned on the bottom panel and has a plurality of LEDs (light sources) mounted in a row along the lengthwise direction on a long substrate.
In the light-emitting unit, the plurality of LEDs are mechanically mounted substantially linearly in one row so that their optical axes are aligned in a fixed direction on the surface of a strip-shaped printed circuit board. The LEDs are so-called power LEDs that can continuously pass a current of 200 mA or more, and are surface mounting-type LEDs in which LED elements are arranged in the center of a rectangular panel-shaped package. The LEDs are disposed, for example, such that the LED elements are aligned at fixed intervals in a single, substantially linear row.
Since a light source such as an LED light source has a useful life, the light source must be periodically exchanged, or exchanged every time a set number of usage hours have elapsed. Therefore, in the above-mentioned line light irradiation device, since each LED light source is fixed to a substrate within the device, when exchanging the LED light sources, the device had to be taken apart to remove the substrate and exchange each LED light source one-by-one or exchange the entire substrate.
However, there have been problems in that this kind of exchange operation required considerable time and labor and the operation efficiency was poor, and the manufacturing line had to be stopped for a long time when exchanging the LED light sources during manufacturing, which led to decreased productivity.
Patent Literature 2 discloses one known example of a line light irradiation device that solves the above-described problems.
This line light irradiation device includes a light source unit obtained by bonding a light source mounting substrate on which a plurality of light sources are mounted in a line shape and a heat radiation member that radiates heat from the light source mounting substrate, a main body housing on which a plurality of the light source units are aligned and mounted, and a drive control part that outputs a drive signal to the light source mounting substrate of each light source unit.
According to this kind of line light irradiation device, when a light source needs to be exchanged due to reaching the end of its life or the like, the light source units can be removed from the main body housing and each light source unit can be exchanged individually. Thus, the maintenance is easy and the operability is improved.